1. Field of the Invention
The present invention relates to construction machines, such as hydraulic excavators, and to a method for manufacturing such construction machines.
2. Description of the Related Art
Hydraulic excavators are generally provided with an upper rotating body which includes a frame. The frame has a bottom plate which is provided with supporters for supporting devices, such as an operating oil tank and a fuel tank.
Conventionally, the supporters are attached to the bottom plate by welding the lower end of each supporter to the top surface of the bottom plate.
In such a case, since the supporters are attached to devices and guard panels, the supporters must be properly adjusted for height and perpendicularity.
However, when assembling together the main components of the rotating body, such as main frame components, there are cases where the bottom plate is bent due to welding distortion. Such bending of the bottom plate is large especially in cases where the thickness of the bottom plate is small with respect to the surface area.
Consequently, this means that the supporters have to be fixed to a slanted surface and thus may deteriorate the perpendicularity of the supporters, and moreover, may lead to improper height setting of the supporters. As a result, this may create difficulties in attaching the devices and the guard panel to the supporters.
Furthermore, other than the welding distortion, there are also cases where the deterioration of the perpendicularity and the improper height setting of the supporters are caused due to a fabrication error in the top surface of the bottom plate or a truncation error in the supporters.
For solving the problem of the welding distortion in the bottom plate, the bottom plate may be heated prior to attaching the supporters so as to fix the distortion. On the other hand, for solving the problem of the fabrication error in the bottom plate or the truncation error in the supporters, such an error in the bottom plate or the supporters may be corrected prior to the welding process by, for example, cutting. Such solutions are possible, but are problematic in view of the fact that they increase the time and number of steps required for manufacture.